砂岩储层石英胶结物的SiO_2来源研究综述

A Review of Research on the Source of Quartz Cements in Sandstone Reservoirs

石英胶结作用是导致砂岩储层致密的重要原因之一,目前关于石英胶结物SiO_2内部或外部来源尚无定论。关于石英胶结物SiO_2来源问题的研究较薄弱,尤其对非晶质SiO_2溶解来源和SiO_2外部来源的研究重视不足。本文在前人研究成果的基础上,重点探讨了致密砂岩储层中石英胶结物形成的成岩作用时间及SiO_2的物质来源,并研究了其贡献量的大小。结果表明:(1)长石的溶解与转化、蒙脱石的伊利石化和绿泥石化作用、压溶作用与缝合线的发育,以及非晶质SiO_2的溶解作用,是砂岩储层中石英胶结物发育的重要内部SiO_2来源。石英胶结物的外部来源则包括岩石邻近的砂体,也包括深部埋藏砂岩、深部埋藏泥岩、花岗岩侵入体、基岩等来源的大规模运移。(2)长石的溶解、蒙脱石的伊利石化和绿泥石化作用、压溶作用与缝合线的发育,主要在早成岩-中成岩时期为砂岩储层提供SiO_2来源,而钾长石向高岭石和伊利石的转化、钠长石化作用主要为中成岩-晚成岩时期石英胶结物的主要SiO_2来源。此外,非晶质SiO_2的溶解和外部来源提供的SiO_2推测应该可以发生在整个沉积成岩时期,且需要进一步研究工作验证。

Cementation is one of the essential cause that why sandstone reservoirs are compacted. Currently, there is no final conclusion about the quartz cements＇ source, which derived internally to the cemented sandstone or externally. And that there are not enough attentions to the source of quartz cements, especially on the source of noncrystalline SiO2 and external sources. Based on predecessor＇s fruits, we summarized and discussed achievements on sources and the diagenetic period of quartz cements in sandstone reservoirs. What＇s more, we tried to explore the contribution of various sources for quartz cements. This study shows that they are main sources of quartz cements, such as dissolution and transformation of feldspar, illitization and chloritization of smectites, pressure solution and stylolite, and dissolution of noncrystalline SiO2. While external sources of quartz cements may be contained adjacent sandstones, deep buried sandstones, intrusive messes of granites, basement rocks, and so on. In addition, during the early diagenesis to the middle diagenesis, they could be the main source of quartz cements, for instance, issolution of feldspar, illitization and chloritization of smeetites, pressure solution and stylolite. While kaolinization and illitization of K-fehlspar may provide the main SiO2 source for quartz cements during the middle diagenesis to the late diagenesis. However, the source of noncrystalline SiO2 and external sources could provide SiO, during the whole diagenetic period. There are much work can be done to reappraise it.